Breast cancer gene involved in skeletal muscle energy metabolism

By Rajendrani Mukhopadhyay

The BRCA1 gene, which is officially known as the breast cancer 1, early onset, gene, is well-known to be expressed in breast tissue. People who have particular mutations in this tumor-suppressor gene are at increased risk of developing certain types of breast cancer. But in work just published in the Journal of Lipid Research, investigators demonstrated the BRCA1 gene also is expressed in skeletal muscle. Espen Spangenburg at the University of Maryland, the senior author on the paper, says that the work indicates that BRCA1’s influence “extends beyond just breast cells.”

Using cells taken from mice and humans, Spangenburg’s team demonstrated that there were multiple isoforms of BRCA1 in skeletal muscle. They then showed that when mice underwent bouts of intense exercise, there were more interactions between BRCA1 and the phosphorylated form of acetyl CoA carboxylase, a critical regulator of lipid metabolism.

When the investigators reduced the BRCA1 content in human skeletal muscle cells in culture, the mitochondria consumed less oxygen. There was also more lipid stored inside cells, and the amount of insulin signaling dropped.

Taken together, the data suggest that BRCA1 is important in regulating energy metabolism in skeletal muscle. Furthermore, the work highlights that this gene plays a role in tissues beyond those involved in reproduction. Spangenburg says, “This is particularly important when one considers the number of known genetic mutations that develop in the BRCA1 gene. We need to consider how these mutations may affect skeletal muscle function.”